Environmental regulations may limit the amount of NOx emitted from turbine engines. One known manner for reducing NOx emissions is to mix the compressed air used for combustion with fuel before the air enters the primary combustion zone. Such premixed fuel burns cleaner than combustion fuel that is not premixed so as to reduce the amount of NOx generated. In addition to the NOx reduction benefit, premixed combustion air can assist in the management of the dynamic forces during combustion. In particular, when the primary combustion zone is provided with a air/fuel premixture, a more stable, controlled and predictable combustion occurs. As a result, the potential for high frequency acoustic combustion forces and their associated dangers are minimized.
A fuel injector assembly can be provided for distributing fuel into the compressed air flow upstream of the main combustor portion of the turbine. In one prior design, fuel is injected into the compressed air stream using a ring-type assembly as shown in FIG. 1. Such a fuel ring may be disposed within a turbine combustor at a location upstream in the gaseous fluid (i.e. airflow) from combustor burners, as shown in FIG. 2. While such fuel rings have permitted improved control of NOx production and dynamic forces when compared to earlier systems, the fuel rings permit only minimal control of the fuel profile within the gaseous fluid flow.